With increase of the number of users in mobile communication system, how to utilize radio spectrum resources more sufficiently and better becomes an important problem to be solved, and now the most commonly used mode is resource multiplexing. In the available mobile communication system, basic radio spectrum resources usually include frequency resources, time resources and code resources, and correspondingly, frequency division multiplexing (FDM), time division multiplexing (TDM), code division multiplexing (CDM), or their combination can be carried out based on those basic radio spectrum resources.
Since the 90s, beamforming techniques are applied broadly in the mobile communication system, and the beamforming technique is significantly applied in two aspects: one is to improve the signal-to-interference ratio of desired user directly by beamforming so as to improve the performance of system or spectrum efficiency; and the other is to multiplex limited spectrum resources by beamforming. Array antenna adopting beamforming technique is usually called smart antenna which aims the main beam to the desired user to perform receiving and transmitting by beamforming, so that the received power of desired signals is increased. The smart antenna may also aim the nulls steering of the array antenna pattern to an interfering user according to space characteristic of the interfering signal by adjusting weighting coefficient of each antenna unit, so that the power of signal from (to) the interfering user is reduced.
Based on beamforming and smart antenna techniques, the concept of space division multiplexing (SDM) brings out in the field of the resource multiplexing. The so-called space division multiplexing refers to the form of multiplexing basic radio spectrum resource unit on the basis of the modes of frequency division multiplexing, time division multiplexing and code division multiplexing by using beamforming techniques of the smart antenna, for instance: different beams are multiplexed in different spatial layers. The basic mind of space division multiplexing is minimizing the interference received between two user's signals when the base station receives signals or minimizing signal of the other user contained in the signal received by any one of the two users when the base station transmits signals, by orthogonalizing channels of two users multiplexing a single radio resource.
However, in the current available solution, only the method for performing interference suppression between two users multiplexing a single resource by beamforming is provided, wherein the interference suppression is performed by aiming the main beam to the desired user and aiming nulls steering to the interfering user by beamforming based on space information of the desired user and the interfering users. However, the performance and effect of the interference suppression between two users cannot be ensured, it totally depends upon beamforming algorithm. Especially, the downlink beamforming is further influenced by error introduced by the beamforming delay. Evidently, the prior art fails to definitely provide a method for realizing space division multiplexing and fails to suggest how to ensure the effect and accuracy of space division multiplexing.